Dry weather could adversely speed tobacco curing

• For burley growers, the dry conditions remind them of this time last year, when much of the tobacco crop was lost in the barn.

By Aimee Nielson, University of Kentucky | Sep 07, 2011

After the wettest Kentucky spring on record, summer delivered much less impressive rainfall; and many parts of the state have slipped into drought status.

For burley growers, the dry conditions remind them of this time last year, when much of the tobacco crop was lost in the barn.

UK Agricultural Meteorologist Mike Mathews said a dry August, combined with the dry end of July, caused drought conditions to expand quickly from west to east across the commonwealth.

“From the beginning of August to the end, drought conditions have gone from nearly no coverage to over 70-percent coverage of the state,” he said.

“Most of that area is abnormally dry. However, 31 percent of the state is in moderate drought and 4 percent has gone into severe drought.”

“Burley growers should be somewhat concerned,” said Bob Pearce, UK Extension tobacco specialist. “Obviously the drought conditions have had a negative impact on burley crop growth, but we’re more concerned with trying to determine the impact of this dry air mass on curing.”

With much of the state’s burley tobacco crop hanging in the barns, Pearce said drier-than-normal conditions across the state could cause the crop to cure too rapidly.

“Anyone involved in burley remembers last year’s events,” Pearce continued. “The dry air resulted in poor curing, low-quality tobacco that was either severely discounted or rejected at the market. A repeat of that situation would really be disastrous to our growers and the entire industry.”

“The latest U.S. drought monitor indicates that parts of Kentucky have moved into severe drought status,” said Tom Priddy, University of Kentucky College of Agriculture meteorologist. “Preliminary numbers show that August was the 17th driest on record. Every week of August recorded below normal rainfall.”

Priddy said dew-point temperatures are on the rise and that could help slow the drying of tobacco in the barns, but burley growers still need to keep a close eye on the situation and take as many damage-control measures as possible.

Slow drying process

To minimize the problems growers faced last season, Pearce said they should take steps at harvest and in the early curing phase to slow down the drying process.

“Giving the crop more time to cure will result in better color development,” Pearce said. “In drought-stressed areas, growers need to minimize the field wilt time. This will allow them to take more moisture into the curing barns.”

In areas where the dry weather has stunted growth, growers may want to consider packing the crop in the barn tighter than normal.

“In some cases, they may want to place sticks as close as 4 to 5 inches apart,” Pearce recommended. “That can reduce airflow through the crop and slow the drying process. With larger crops, I still recommend normal stick spacing.”

When the average daily relative humidity is at least 75 percent, growers should keep barns open, however below that, growers should consider closing the barn doors and vents during the heat of the day even with relatively green tobacco in the barn.

“One of the lessons from last year was that once we lost the initial moisture in the crop there was no getting it back,” Pearce explained. “The crop simply dried and the color did not change much after that.”

He recommends that growers monitor closed barns (especially those with green tobacco) very closely by checking them at least once a day, looking and smelling for signs of rot setting in.

At the first sign of houseburn, growers should open and flush the barn for a few days.

“For newer barns with no vent doors or in some cases no sides, growers may want to consider covering the openings with plastic or house wrap to slow airflow and minimize drying,” Pearce added. “As the tobacco progresses through yellowing, growers may need to close barns for longer periods of time.”

Priddy said the dry pattern has also impacted other agricultural areas.

“Combined with the late start to planting and dry weather, corn and soybeans are behind the 5-year average of where they should be in every stage of growth,” he said.

“Pond levels are low. Temperature-wise, the state got some relief from the previous summer months, with near seasonal normal temperatures almost every week. Most locations such as Louisville, Lexington, Paducah and London were right around their average days at or above 90 degrees, which was not the case just one month ago.

However; Bowling Green did have 25 days at or above the 90 degree mark, well above their normal for August.”